This invention relates to a circuit for controlling the operability of one or more cylinders of a multicylinder internal combustion engine. Prior art U.S. patents for accomplishing this purpose include Rohlin U.S. Pat. No. 2,166,968 issued July 25, 1939; Winkler U.S. Pat. No. 2,652,038 issued Sept. 15, 1953; Dolza U.S. Pat. No. 2,875,742 issued Mar. 3, 1959; and Mick U.S. Pat. No. 2,918,047 issued Dec. 22, 1959.
As the above patents indicate, it is known and desirable to increase the efficiency of a multicylinder internal combustion engine by reducing the number of cylinders on which the engine operates under predetermined engine operating conditions, particularly conditions of low engine load and under selected engine speed conditions. The above patents generally describe control systems for disabling a number of cylinders in a multicylinder internal combustion engine by suppressing the supply of fuel to certain cylinders or by preventing the operating of the intake and exhaust valves of selected cylinders. Under given engine speed and load conditions, the disablement of some of the cylinders of the engine increases the load on those remaining in operation and, as a result, the energy conversion efficiency is increased. The prior art systems, however, have been generally mechanically complex and quite expensive in practical implementation. The present invention obviates these difficulties of the prior art controls and permits a substantial improvement in fuel economy to be obtained in a multicylinder internal combustion engine equipped in accordance with the invention.